what you have to realise, is your asking a landowner to let you, walk over his land, with an air rifle, shooting things, he has to trust, that you
1, are going to respect his land, not take everyone and their uncle with you, shut gates, not trampel feilds, not shoot livestock etc etc
2, only shoot pest species
therefore you have alot to prove to him, even before he say's yes
1st get yourself insured for public liability, look on this forum for insurers
2nd, maybe BISLEY safe use of airguns certificate
3rd maybe a place to get rid of unwanted carcases, ie, you may want to keep shot rab